In semi-conductor components, more particularly memory components such as DRAMs (DRAM=Dynamic Ransom Access Memory and/or dynamic read/write memory) an internal voltage level VINT used inside the component may differ from an external voltage supply (supply voltage level) VDD made available to the semi-conductor component.
In particular the internally used voltage level VINT may be lower than the level VDD of the supply voltage—for instance the internally used voltage level VINT may amount to 1.5 V, and the supply voltage level VDD for instance to between 1.5 V and 2.5 V, etc.
An internal voltage level VINT that is lower than the supply voltage level VDD has the advantage of allowing power dissipation inside the semi-conductor component to be reduced.
In addition, the voltage level VDD of the external voltage supply may be subject to relatively strong fluctuations. Therefore in order for the component to operate in as fault-free a manner and/or as reliably as possible, the supply voltage is generally converted—by means of a voltage regulator—to an internal voltage VINT (which is subject only to relatively minor fluctuations and regulated to a certain constant lower level).
Conventional voltage regulators (for instance corresponding down-converters) may for instance contain a differential amplifier and a p field effect transistor. The gate of the field effect transistor can be connected to an output of the differential amplifier and the source of the field effect transistor for instance to the external voltage supply.
A reference voltage VREF—subject only to relatively minor fluctuations—is applied to the negative input of the differential amplifier. The voltage emitted at the drain of the field effect transistor can then be directly back connected to the positive input of the differential amplifier, or for instance with a voltage splitter interposed.
The differential amplifier regulates the voltage present at the gate connection of the field effect transistor to such an extent that the (back-connected) drain voltage—and therefore the voltage emitted by the voltage regulator—remains constant and at the same time level as the reference voltage, or for instance higher by a particular factor.
In order to generate the above reference voltage VREF, an appropriate conventional reference voltage generating device, for instance a band-gap reference voltage generator can be used, which can—for instance by means of one or more diodes—generate a signal VBGR at a constant voltage level from the supply voltage (exhibiting the above relatively high supply voltage level VDD and occasionally possibly subject to relatively strong voltage fluctuations).
The signal at the constant voltage level VGBR can be fed to a buffer circuit, where it is (temporarily) retained, and then relayed further—in the form of signals at the above reference voltage level VREF—(for instance to the above voltage regulator (and/or the negative input of the corresponding voltage regulator differential amplifier) and/or further devices provided on the semi-conductor component, for instance further voltage regulators)).
The level of the internal voltage VINT emitted by each voltage regulator must be pre-set at such a low level that—taking into account all possible manufacturing faults such as inaccuracies and/or deviations—the semi-conductor component can be reliably operated under all conditions (for instance even with the briefest possible gate length of the transistors, connected to the internal voltage).
With—for instance—longer (actual) gate lengths, etc. the internal voltage VINT selected in the above manner is lower than it could be, which leads to losses in performance.